1. Field of the Invention
The present invention relates generally to a water preclusion device for an engine, and more particularly to an improved water preclusion device using a valve controlled by in-cylinder pressure.
2. Brief Description of Related Art
Various watercraft engines with partially submerged exhaust systems which open to a body of water, typically incorporate a water preclusion device. When such an engine is running, the exhaust gases are discharged into the body of water through the exhaust pipe under a positive pressure. This positive pressure prohibits water from flowing into the engine. However, as soon as the engine stops, water can enter the exhaust pipe and cause damage.
Many modern watercraft include elevated inverted-U shaped high-riser exhaust pipes placed above the water line to prevent the invasion of water when the engine stops. Incorporating a high rise pipe in the exhaust system requires ample space and results in a high profile and a higher center of gravity.
Designing the engine compartment of low profile, compact, internal combustion engine-powered watercraft requires special consideration. Such low profile watercraft provide improved handling due to a low center of gravity and overall compact design. However, such watercraft do not accommodate high-rise type exhaust systems.
Thus, certain low-profile watercraft designs have incorporated spring-biased valves opened by exhaust pressure and which close as exhaust pressure drops. Relatively weak springs are used to reduce or eliminate back pressure in the exhaust system. However, such relatively weak springs are limited in that they do not provide sufficient pressure to completely seal the valve and thus allow water to enter under certain conditions.